A. Field of the Invention
The invention relates to a method and an apparatus for the detection and recognition of malfunctions in one or more cylinders of an internal combustion engine. More particularly, the invention relates to the detection of such malfunctions on the basis of periodic fluctuations of the torque or the rpm of the engine.
B. State-of-the-Art
Known in the art are methods and devices for recognizing malfunctions of the engine in timely manner. Included in this overall category are the well known oil pressure gauges or warning lights and cooling medium temperature gauges. However, these devices only permit deductions as to the malfunction of particular cylinders of an engine and only after a malfunction of other engine components.
Also known in the art are devices which recognize malfunctions in the catalyzers of exhaust gas systems in internal combustion engines. For example, when the catalyzer temperature exceeds a predetermined level, these devices determine which of the cylinders of the engine is not performing properly, for example due to a failure of ignition. However, these devices are not suitable for determining malfunctions due to other causes, for example faulty compression due to excessive wear, defective piston rings or cylinder head gaskets, as well as because of faulty valves.
Also known in the art are fuel control processes which gather data as to the roughness of the engine operation and use this data for comparison with the nominal rpm of the engine and the results of the comparison are then used to adjust the fuel-air mixture to reduce excessive engine fluctuations.